Butylene linked palladium N-heterocyclic carbene complexes: Synthesis and catalytic properties

New bis(NHC)–Pd complexes were synthesized and characterized by elemental analysis, 1H NMR, 13C NMR, and IR spectroscopy. The reaction of Pd(OAc)2 and bis(benzimidazolium) salts in DMSO gave the monomeric palladium complex in which the N-heterocyclic carbene was bound to the metal centre. The crystal and molecular structure of the cis-dibromo{1,1′-di[2,3,4,5,6-pentamethylbenzyl]-3,3′-butylenedibenzimidazol-2,2′-diylidene}–palladium(II) complex was determined by single-crystal X-ray diffraction. The activity of the Pd(II) complexes in the direct arylation of benzothiazole with arylbromides was investigated. A preliminary catalytic study showed that these bis(NHC)–Pd complexes were highly active in the direct arylation of benzothiazole with arylbromides.

Graphical abstractChelating bis(NHC)–Pd complexes were synthesized and characterized structurally and spectroscopically. All palladium complexes display high activities in the direct arylation of benzothiazole with arylbromides.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Synthesis and characterization of chelating bis NHC-Pd complexes. ► The complex was determined by X-ray diffraction. ► The activity of these complexes in the direct arylation of benzothiazole with arylbromides was investigated.